A wide variety of lettuce-type greens including baby leaf spinach, tango, lolla roas, red oak leaf, baby romaine, green oak leaf, baby red romaine, baby red chard, red mustard, Totsoi, Mizuma, Frisee, arruagula, radicchio, and curly endives are currently grown, and are typically referred to in the trade under the term “baby greens.” They are harvested well before maturity for freshness and tenderness. Baby greens are typically used for mixed or one of a kind salads and garnishes in restaurants and in pre-packaged bags available at grocery stores. Shelf life is critical to the greens market. It takes a significant amount of time after harvest for the greens to pass through processing and distribution to market. Greens crush and bruise easily, and subsequently wilt and discolor to brown within a matter of hours. Wilted and bruised greens leaves are undesireable. Therefore, great care must be taken in handling the greens through the entire process of harvesting and moving the product from the field to the market. To minimize damage during harvesting, greens must be severed without pulling, tearing or shredding, and must be handled gently as they are transported from the field.
Currently, growers are using both manual harvesting and machine harvesting of baby greens. Each of the prior harvesting means has disadvantages. Manual harvesting of baby greens requires many farm laborers to enter the fields and kneel or lean across the bed to sever the stems of the baby greens adjacent to the earth with a knife or sickle. The laborer then places the severed greens by hand into carrying boxes called totes, which are stacked in pallets for transportation. Manual harvesting has a number of significant disadvantages. Firstly, the cost of the numerous laborers is high. Second, the low height of the baby greens means that when the top is gripped by the worker, the worker must cut fairly close to his or her hand, and as a result, many workers are injured in the fields. Third, hand harvesting necessarily limits the width of the beds to 36 to 48 inches between furrows, which is a width reachable by the workers. Narrower furrows have the adverse effect of reducing the yield per acre of product from the yield that could be obtained with wider furrows. Fourth, the harvest period for hand harvesting is typically from 6:00 am to 10:00 am in the morning, before which it may be too dark for the workers to work safely, and after which the whether may be too hot as the cut greens will wilt too fast. Thus in a typical 3-4 hour cutting day, a working can produce only about 15 totes. Lastly, it is not possible to get an accurate and uniform even cut at a specified height when harvesting by hand.
A number of self-propelled harvesters have been developed to harvest baby greens. These harvesters overcome some of the problems encountered in harvesting by hand, however, a number of other problems have been encountered. For example, Prior art harvesters have been complicated and expensive to purchase and maintain some prior art harvesters are extremely heavy vehicles. Furthermore, the high weight of such harvesters can disrupt the structure of the furrows, possibly requiring that the field be replowed after each harvest. The high weight and size of these harvesters can make the prior harvesters difficult to transport from field to field. Lastly, the cutting and collecting methods used by prior harvesters frequently results in damage to the delicate baby greens.
Whether the baby greens are harvested by hand or by machine, it is preferred that the harvested baby greens consist mostly of whole leaves, and that smaller pieces and cotyledon leaves be discarded. Sorting baby greens is difficult after the leaves have been harvested and placed in totes or other storage containers because the leaves tend to clump together.
What is needed is a harvester that is lightweight, inexpensive to maintain, and that will harvest the greens in a manner optimal to retaining freshness and shelf life, and that can sort the cut greens in the field to remove unwanted material before the product becomes bunched in storage containers.